byNASA -- Animation by Jesse Allen, NASA GSFC, based on data from the www.jpl.nasa.gov/srtm/ Shuttle Radar Topography Mission and landsat7.usgs.gov/ Landsat 7.
The Kuiseb River in Namibia is bordered on one side by the tallest sand dunes in the world, and on the other by barren rock. The red sand dunes south of the river reach heights over 150 meters. The prevailing winds blow the dunes northward, but their movement is blocked by the river. In the process, so much sand and silt is deposited in the Kuiseb that it only reaches the sea while it is in flood. Topic: Where -- Namibia Source: http://earthobservatory.nasa.gov/IOTD/view.php?id=768
byNASA -- Image courtesy NASA Goddard Space Flight Center, svs.gsfc.nasa.gov/ Science Visualization Studio
The fires that raged across southern Africa this August and September produced a thick ''river of smoke'' over the region. NASA-supported studies currently underway on the event will contribute to improved air pollution policies in the region and a better understanding of its impact on climate change. This year the southern African fire season peaked in early September. The region is subject to some of the highest levels of biomass burning in the world. The heaviest burning was in western... Topics: What -- NOAA 14, Where -- Virginia, What -- Earth, What -- Spectrometer, Where -- Zambia, Where --... Source: http://earthobservatory.nasa.gov/IOTD/view.php?id=963